The present invention relates generally to mechanisms for filling bags and particularly to a rotary flow control device for an auger bag filling system designed for depositing a predetermined charge of particulate materials into a bag.
Rotary feed auger systems for dispensing particulate materials into containers are well known in the art. These systems are very useful for rapidly depositing a gross charge of particulate material within a container. However, a common shortcoming shared by rotary feed auger systems is that they have difficulty in filling containers to within a specific low tolerance. This stems from the fact that the open end of a rotary feed auger system does not adequately contain particulate material therein when the auger is not operating. Therefore, quantities of particulate material may fall from within the fill tubes of these rotary feed auger systems before or after the rotary feed auger system has dispensed a presumably accurate charge quantity of particulate material into the container. Such errors are not as critical when the containers being filled are relatively large. However, when the containers being filled are of a small to moderate size, it is often necessary to include a separate top-off station with the rotary feed auger system to insure that the container has the desired charge weight of particulate material deposited therein.
Accordingly, it is an object of the present invention to provide a structure that will increase the accuracy and precision with which a rotary feed auger system dispenses particulate materials into a container.
The objects of the present invention are met by a rotary flow control device that comprises a stationary plate and a rotary plate. The stationary plate of the present invention has a plurality of flow openings formed therethrough and coupled to the discharge end of a fill tube of the container filling system so as to create a flow obstruction of sufficient magnitude to compact a particulate material flowing through the fill tube. The rotary plate of the present invention is operatively disposed adjacent the stationary plate and also has a plurality of flow openings formed therethrough. The rotary plate is constructed and arranged to rotate with respect to the stationary plate in such a manner that the flow openings formed through the rotary plate periodically come into alignment with the flow openings of the stationary plate, thereby allowing the compacted particulate material to flow through the respective flow openings. The rotation of the rotary plate with respect to the stationary plate acts to shear off portions or masses of the particulate material that has flowed or has been extruded or conveyed through the respective flow openings of the stationary and rotary plates.
Preferably the rotary flow control device with which the present invention is utilized will also include an auger that is disposed within the fill tube of the container filling system for conveying particulate materials therethrough. Where this is the case, the shaft o the auger will be made to pass through the stationary plate so that the rotary plate may be coupled thereto. Consequently, in this preferred embodiment, the rotary plate will be constrained to rotate with the shaft of the auger. However, where an auger is used, it is also preferred to space the flights of the auger a predetermined distance from the stationary plate. In one embodiment, this distance is approximately two inches.
The flow openings formed through the stationary plate are defined by a plurality of ribs that have a tapered cross section such that the flow openings are narrower at an exit side than they are at an entrance side. This arrangement increases the compacting ability of the stationary plate. Preferably the side surfaces of the plurality of ribs that define the flow openings are tapered at approximately 15 degrees from an axis defined by the central axis of the fill tube.
In order to enhance the flow of particulate materials from a supply hopper and through a fill tube coupled to an outlet thereof, it is often desirable to couple the supply hopper to a vibrating mechanism for vibrating the supply hopper to at least partially fluidize a quantity of particulate material disposed therein. Similarly, a hopper may be provided with a wiper assembly comprising a wiper constructed and arranged to move along an inner surface of the supply hopper so as to prevent the adhesion of a particulate material contained within the supply hopper to the inner surface of the supply hopper.
Another feature that improves the flow of particulate materials through an auger fed container filling system incorporates an interrupted screw auger comprising a shaft having affixed thereto an upper section of flights that is disposed entirely within the supply hopper and an lower section of flights that is disposed entirely within the fill tube. The upper and lower sections of flights are beneficially separated by a space of predetermined length generally located at the juncture between the fill tube and the supply hopper. Where the interrupted screw auger is utilized it is often preferred to utilize an auger having an upper section of flights with a diameter that is larger than the diameter of the lower section of flights thereof. The upper section of flights, regardless of its diameter, is ideally positioned within the supply hopper to act upon the particulate material contained therein so as to move the particulate material toward the fill tube coupled to the supply hopper. It is to be understood that the present invention may be used with any combination of the aforementioned vibrating mechanism, wiper assembly, and interrupted screw auger, or even without.
The present invention may alternatively be stated in terms of an auger feed container filling system comprising a supply hopper having an inlet and an outlet, a fill tube having an upper end and a lower end, with the upper end of the fill tube being coupled to the outlet of the supply hopper, an auger comprising a shaft and at least one section of flights disposed within the fill tube, and a rotary flow control mechanism coupled to the lower end of the fill tube. The rotary flow control mechanism itself comprises a stationary plate that is coupled fixedly to the lower end of the fill tube and a rotary plate coupled to the shaft of the auger as it extends through a central bore in the stationary plate such that the rotary plate is positioned adjacent the stationary plate opposite the lower end of the fill tube. The stationary plate has a plurality of flow openings and a central bore formed therethrough. The flow openings of the stationary plate are bounded by and defined at least in part by a plurality of ribs. The rotary plate also has formed therethrough a plurality of fill openings, with the flow openings being bounded by and defined at least in part by a plurality of ribs. The flow openings of the rotary plate and the stationary plate are constructed and arranged such that as the rotary plate rotates in relation to the stationary plate, the flow openings of the respective plates will at least partially become aligned with one another so as to allow the flow of a particulate material being conveyed by the auger through the respective plates of the rotary flow control device. As the rotary plate continues to rotate with respect to the stationary plate, the ribs defining the flow openings of the rotary plate will act to shear off particulate material that has flowed through the at least partially aligned flow openings of the stationary and rotary plates. The action of the auger against the rotary flow control device is such that the particulate material is compacted to a degree that limits the incidence of particulate material falling from the fill tube when the auger is not operational. A bag support and handling mechanism is provided to support a bag adjacent the rotary flow control device for filling.
The auger utilized with the auger fee container filling apparatus may be one of any configuration but in one preferred embodiment, the auger will be an interrupted screw auger comprising a shaft that extends through the supply hopper and fill tube, an upper section of flights disposed entirely within the supply hopper, and a lower section of flights disposed entirely within the fill tube. The at least one section of flights of the auger disposed within the fill tube is spaced away from the rotary flow control device by a predetermined distance that in one embodiment is approximately 2 inches.
The edge profiles of the flow openings in the stationary plate are preferably at least partially tapered such that the entry side of the flow openings is larger than the exit side of the flow opening. The taper imparted to the edge profiles of the flow openings of the stationary plate is sufficient to at least partially compact a particulate material flowing through the at least partially aligned flow openings of the stationary and rotary plates. In one embodiment, the taper of the edge profiles of the flow openings of the stationary plate is approximately 15 degrees from an axis defined by the central axis of the fill tube.
Where the rotary flow control device is to be used with extremely flowable particulate materials, the device may comprise a stationary plate having a plurality of flow openings formed therethrough with the flow openings being separated by a plurality of ribs. The stationary plate is coupled to a discharge end of a fill tube of a container filling system so as to create a flow obstruction of sufficient magnitude to at least partially compact a particulate material flowing through the fill tube. A plurality of baffles is affixed to an upper surface of the ribs of the stationary plate. The baffles simultaneously compact and direct the particulate materials into the flow openings of the stationary plate. A rotary plate is coupled to the container filling system and disposed adjacent the stationary plate. The rotary plate also has a plurality of flow openings formed therethrough and is constructed and arranged to rotate with respect to the stationary plate in such a manner that the flow openings formed through the rotary plate periodically come into alignment with the flow openings of the stationary plate. This period alignment allows the compacted particulate material to flow through the respective flow openings so that the rotation of the rotary plate may also act to shear off portions of the particulate material that has flowed through the respective flow openings of the stationary and rotary plates. This embodiment may or may not comprise an auger of standard or interrupted screw configuration. Where an auger is utilized with the fill tube, the shaft of the auger will extend through the stationary plate so that the rotary plate may be coupled to the end thereof. Another feature of this embodiment is that the flow openings of the rotary plate may be positioned out of alignment with the flow openings of the stationary plate when the auger is stationary so as to completely close off the lower end of the fill tube. In this manner, no particulate material will be able to exit the fill tube when the flow openings of the respective plates are so misaligned.
Yet another rotary flow control device for a container filling system comprises a stationary plate that has a plurality of flow openings formed therethrough, with the stationary plate being coupled to the discharge end of a fill tube of the container filling system so as to create a flow obstruction of sufficient magnitude to compact a particulate material flowing through the fill tube and a rotary plate rotatably coupled to the stationary plate adjacent the stationary plate. The rotary plate also has a plurality of flow openings formed therethrough and is constructed and arranged to rotate with respect to the stationary plate in such a manner that the flow openings formed through the rotary plate periodically come into alignment with the flow openings of the stationary plate, thereby allowing the compacted particulate material to flow through the respective flow openings. The rotation of the rotary plate also acts to shear off portions of the particulate material that has flowed through the respective flow openings of the stationary and rotary plates. In the absence of an auger shaft, the container filling system may further comprise an independent drive mechanism that is operatively coupled to the container filling system so as to rotate the rotary plate with respect to the stationary plate.
These and other objectives and advantages of the invention will appear more fully from the following description, made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.